Bridge crane, especially a container-loading bridge

ABSTRACT

A bridge crane, especially a container loading bridge, having a portal, a boom, a track system laid on the boom and crane trolleys which travel on the tracks, in which the track system comprises a working track, whose two rails have a mutual spacing corresponding to the wide spacing of the running wheels of the crane trolleys in a working position and a return track, whose rails have a mutual spacing corresponding to the narrow spacing of the running wheels of the crane trolleys in a return position is provided. Two arched pieces are arranged about the area of the ends of the boom where the working track and return track meet. The two wheel suspension mechanisms of the crane trolleys are constructed so as to rotate freely about a vertical axis. The two rotation axes of the crane trolleys are arranged with a spacing with respect to the longitudinal axis thereof corresponding to half the mutual spacing of the two rails of the return track.

PRIOR APPLICATIONS

This application is a §371 U.S. National Phase application which basespriority on International Application No. PCT/DE00/01842, filed Jun. 7,2000, which in turn bases priority on German Application No. DE 199 26182.2, filed Jun. 9, 1999.

BACKGROUND OF THE INVENTION

1. Field of Invention

The invention relates to a bridge crane having a portal, a boom, a tracksystem laid on the boom and crane trolleys which travel on the tracks.

2. Description of the Prior Art

The problem arises with bridge cranes, particularly container loadingbridges, such as are more particularly used for loading and unloadingcontainer ships, that if there is only a single track, it is onlypossible to use in unhindered manner a single trolley. This considerablyrestricts the capacity of such bridge cranes.

German utility model DE 197 03 282 A1 discloses a container loadingbridge in which, besides the working track which guides the trolleyextending transversely to said track when the trolley is carrying aload, has a return track comprising a single rail and running laterallyalongside the same, and on which the crane trolley extendslongitudinally to the direction of travel, the wheel suspensionmechanism of the crane trolleys being rotatable about a vertical axis inorder to permit the change from the longitudinal orientation to thetransverse orientation.

The known system is advantageous compared with the hitherto knownproposals, but suffers from the disadvantage that as a result of the useof a single rail for the return track, problems can arise with respectto the running stability.

The problem of the invention is to improve the system known from GermanUtility Model DE 197 03 282 A1 with respect to the running stability ofthe crane trolleys to be returned.

SUMMARY OF THE INVENTION

According to the invention, this problem is solved by the features ofclaim 1. Claim 2 gives advantageous developments of the invention.

The invention is described in greater detail hereinafter relative to twodrawings of two embodiments of the track system in diagrammatic form.With regards to other details of the bridge crane construction,reference is made to German Utility Model DE 197 03 282 A1.

DESCRIPTION OF THE DRAWINGS

Further advantages and features of the invention can be gathered fromthe following description of a preferred embodiment of the inventionwith reference to the attached drawings, wherein:

FIG. 1 shows a bridge crane according to the preferred embodiment of thesubject invention with an elongated track construction utilizing switchpoints; and

FIG. 2 shows an alternate embodiment of the subject invention withoutswitch points wherein a loop track construction is employed.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

The track system comprises a working track 10, whose two rails have amutual spacing corresponding to the wide spacing of the running wheels12 of the crane trolleys 14 in a working position, a return track 16,whose two rails have a mutual spacing corresponding to the narrowspacing of the running wheels 18 of the crane trolleys in a returnposition, as well as two arched pieces 19 and 20 located in the vicinityof the ends of a boom, where the working track 10 and return track 16merge into one another. In order to permit a return of the cranetrolleys 14 on the narrow return track 16, a two wheel suspensionmechanism of the trolleys 14 are freely rotatable about a vertical axis22. In addition, two rotation axes of the crane trolleys are positionedwith respect to a longitudinal axis thereof with a section correspondingto half the mutual spacing of the two rails of the return track 16, sothat the crane trolleys 14 on the return track 16 extend longitudinallywith respect to the latter (without such a displacement, the trolleys 14would be inclined with respect to the return track 16).

In the embodiment shown in FIG. 1, the inside rail of the two rails ofthe working track 10 has a substantially elongated construction. In thevicinity of opposed ends 26 and 28 of said rail and spaced from the ends26 and 28 switch points 24 are provided, which connect the inner rail ofthe working track 10 with the inner rail of the return track 16.

In the embodiment shown in FIG. 2, the inner rail of the working trackat the two ends of the boom, and without switch points, passes by meansof a loop into the inner rail of the return track 16.

What is claimed is:
 1. A bridge crane track system for permitting acrane trolley to move along the track system, the crane trolley having aset of running wheels engaging the bridge crane track system, the bridgecrane track system comprising: a) a working track having a first and asecond rail member positioned in a spaced apart and parallelrelationship, the set of running wheels of the crane trolley travelingalong the working track first and second rail members in a firstdirection, b) a return track having a first and a second rail memberpositioned in a juxtaposed and parallel relationship to each other, theset of running wheels of the crane trolley traveling along the returntrack first and second rail members in a second direction opposed fromthat of the first direction, c) an arched piece of track positioned ateach opposed end of the track system connecting the working track andreturn track; and d) the crane trolley positioned transversely withrespect to the working track when traveling thereon and longitudinallywith respect to the return track when traveling thereon.
 2. The bridgecrane track system according to claim 1, wherein the second rail memberof the working track is an inner rail.
 3. The bridge crane track systemaccording to claim 2, wherein the working track inner rail issubstantially elongated and has a pair of opposed terminal ends.
 4. Thebridge crane track system according to claim 3, wherein the second railmember of the return track is an inner rail having a pair of opposedangled portions which connect to portions of the working track innerrail at a position proximal to the opposed terminal ends thereof.
 5. Thebridge crane track system according to claim 4, wherein a pair ofswitching points are provided which facilitate the connection betweenthe working track inner rail and the return track inner rail.
 6. Thebridge crane track system of claim 1, wherein the working track firstrail member and the return track first rail member are connected to oneanother.
 7. The bridge crane track system of claim 6, wherein theworking track first rail member and the return track first rail memberform a continuous looped single rail member of the bridge crane tracksystem.
 8. The bridge crane track system of claim 7, wherein thecontinuous looped single rail member of the bridge crane track system isoval-shaped.
 9. The bridge crane system of claim 1, wherein the secondrail member of the working track is a first inner rail and the secondrail member of the return track is a second inner rail, the first andsecond inner rails connected to one another as an inner continuoussingle rail member of the bridge crane track system.
 10. The bridgecrane system of claim 9, wherein the inner continuous single rail memberof the bridge crane track system has a pair of elongated substantiallyparallel rail portions and a pair of opposed tear drop-shaped endportions.
 11. The bridge crane system of claim 10, wherein the workingtrack first rail member and the return track first rail member areconnected to one another as an oval-shaped outer continuous single railmember.
 12. The bridge crane system of claim 11, wherein the opposedtear drop-shaped end portions of the inner continuous single rail memberare each positioned juxtaposed to opposed end portions of theoval-shaped outer continuous single rail member.